1. Field of the Invention
This invention relates to an underground locating apparatus which includes a wire connected to a signal generator and carried by a hose or cable, which wire transmits a signal that is detected by an above ground receiver.
2. DESCRIPTION OF THE PRIOR ART
Apparatus for unclogging and or cleaning underground pipes is in widespread use. Typically such apparatus includes a head, which is attached to a hose connected to a source of water under pressure. The head and hose are fed into a pipe to be cleaned or unclogged, and water under pressure is introduced into the hose and comes out of the head blasting away debris or obstructions in the pipe. The direction of the water jet also forces the head forward, pulling the hose through the pipe. Examples of such devices are shown in the Kirschke U.S. Pat, No. 3,656,694, Johnson U.S. Pat. No. 3,937,404, Sato U.S. Pat. No. 3,959,840, Klein U.S. Pat. No. 4,312,679, Marsau U.S. Pat. No. 4,687,011, and Larson U.S. Pat. No. 4,756,324. Typically, the pipe to be cleaned or unclogged is underground at and undetermined location and depth, with branches and unknown diversions from a straight and determinate path. Additionally many times tree roots have grown into the pipe, or portions of the pipe have caved in, preventing travel to the head and requiring that the pipe be dug up for cleaning and repair. In order to minimize the time and expenditures involved in digging up the clogged pipe it is highly important to be able to locate the exact location and depth of the clogged pipe as quickly and accurately as possible.
Underground obstruction and observation devices are also used by the electric and telephone utilities to locate problems in their underground conduits and the precise location of the problem is very important to minimize disruption of service and cost. Such devices typically involve a head which may contain a video camera connected to a cable which head also carries a transmitter as previously described.
Various devices have been proposed for locating the head of the cleaning device and hopefully the obstruction such as those shown in the Lowy U.S. Pat. No. 1,662,429, Pearson U.S. Pat. No. 2,558,977, Brenholdt U.S. Pat. No. 2,601,248 and Bell U.S. Pat. No. 2,820,959. Such devices typically require a transmitter carried on the head, which emits a signal that is detected by an above ground receiver. U.S. Pat. No. 4,573,829 to Keene et al discloses a fish wire and transmitter for locating plastic pipe. The Keene device employs a length of flexible piano wire connected to a transmitter at the home end of the wire. No prior art of which the applicant is aware teaches or suggests an antenna wire for locating underground pipe which employs the construction and selection of materials discovered and claimed by the applicant. No prior art device is capable of the performance of applicant's invention.
Many of the pipes with which the devices are used are of cast iron, which causes considerable difficulty in transmitting and detecting the signals emitted from the head due to interference from the metal pipe. In addition other utilities such as electricity and telephone are often in the same location as the pipe being cleaned, with the result that they detect false and spurious signals because of "signal jumping" resulting in wasted time and considerable needless expense.
The apparatus of the invention provides a signal that permits the entire hose or cable and head to be detected both as to location and depth and which provides various other advantages.